The U.S. Supreme Court was poised Thursday to rule on the constitutionality of President Barack Obama\'s landmark healthcare reform law. A decision is not only expected to shape national healthcare policy, but to have an impact on the presidential election in November. The main issue is whether Congress had the power to require everyone who can afford it to buy some kind of health insurance or else pay a fine. But the justices also are considering whether the 1867 Anti-Injunction Act, which bars suits against the federal government over a \"tax\" until the tax actually goes into effect and someone actually is required to pay it, applies to the challenge by 26 states to the individual mandate. The mandate goes into effect in 2014. The states also are asking the Supreme Court whether Congress can require states to choose between complying with the Patient Protection and Affordable Care Act or face losing federal Medicaid funding. The 26 states complained to the court the law sets off \"a massive expansion of Medicaid by requiring all participating states (which is to say, all states) to offer Medicaid to all individuals under the age of 65 with incomes up to 133 percent of the poverty level, with a 5 percent \'income disregard\' provision that effectively raises that number to 138 percent. ... In addition to providing coverage for these newly eligible individuals, states must also provide coverage for millions of individuals who are uninsured despite being currently eligible for Medicaid, as those individuals will be forced onto the Medicaid rolls by the individual mandate.\" The states said the bipartisan Congressional Budget Office \"predicts that at least 16 million individuals will enroll in Medicaid as a result of the combined effect of the expansion and the mandate, and that the federal component of Medicaid spending will increase by $434 billion by 2020 to cover the costs generated by that massive increase in enrollment.\" Medicaid is funded by the national and state governments, but managed by the individual states under federal guidelines. If the justices strike down the individual mandate, they also must decide whether that provision can be \"severed\" to save the rest of the law. It was unclear whether the court would rule on all those issues in one decision, or whether it would use three decisions to represent the three days of separate argument in late March. The White House was upbeat on a Supreme Court decision. \"The constitutionality of the Affordable Care Act depends not on public opinion of polls, but on legal precedent, which is well established,\" press secretary Jay Carney told reporters Wednesday. \" ... Many, many legal scholars have spoken to it. Several very prominent conservative jurists have ruled in favor of the constitutionality of the Affordable Care Act because of their view of that precedent. The fact is the Affordable Care Act gives hardworking middle-class families the security they deserve. And we are confident that the law is constitutional ... and that\'s why we\'re focused on implementing the law.\"